There has been substantial acceptance and growth of the waterbed industry without, however, significant success having been made in solving certain basic structural and operative problems in the waterbeds themselves. As evidenced by U.S. Pat. Nos. 4,062,077, 3,840,921 and 3,849,814, it is known to provide a large unitary flexible water bladder or liner which provides a substantial sleeping surface area. As may be seen from U.S. Pat. No. 3,849,814, a heavy rigid outer framework, essentially a box frame, can be disposed around the outer periphery of the bladder, to provide only peripheral support. As shown in later filed U.S. Pat. No. 3,840,921, the bladder can instead be bordered by a frame having an inclined surface, so that there is less possibility of encounter with the side frame. Alternatively, as shown in yet later U.S. Pat. No. 4,062,077, the area of the bladder can be somewhat reduced, and the bladder can be encompassed not only by a heavy rigid framework, but also by a resilient side edge of rectangular cross-section which, together with interior padding, helps to provide a firmer margin and mechanical isolation from the rigid framework.
As will be evident upon examining the above-referenced patents, all are subject to several common deficiencies of waterbed mattresses. First, a single large support frame and also a heavy bladder or linear must be employed, and these are difficult to ship and handle even in the unloaded form. Second, the flexible bladder is subject to wave motion, or continuing oscillating response to relatively small motions, and for most persons this is a disturbing and generally unwanted characteristic. Third, the bladder cannot be filled or emptied in the normal bedroom location without using tubing or some type of connection to the closest adjacent water source. It is not feasible to fill a mattress averaging some 500 lbs. and transfer the mattress from one room to another. In addition, once the mattress has been filled it cannot readily be moved for the same reasons. Fourth, should a leak occur during the years in which a mattress is to be used, the most common way in which the leak can be located and remedied is to empty the mattress before or after locating the leak, then to effect the repair, which may require return to the store, and then to refill the mattress. An undetected leak can substantially damage a bedroom and its furnishings, and the dangers of such leakage are well recognized. Further, the weights involved with the heavy frame, large bladder and the large volume of water needed often exceed the permissible floor loading in a residence or apartment structure. In consequence of these factors the practice of prohibiting the installation of waterbeds in apartments has become widespread.